1. Field of the Invention
This invention relates to a disc assembly of the type primarily used on a wheel for an automobile or like motor vehicle wherein the brake lining is movable into and out of frictional engagement with the disc attached to the wheel and further wherein the lining is capable of independent movement relative to the disc so as to accomplish increased frictional engagement therebetween in order to increase the braking action between the lining and the disc and connected wheel.
2. Description of the Prior Art
The majority of prior art braking assemblies utilized for motor vehicle applications included a shoe-type brake which generally is internally expanded and hydrolically operated. However, the disc brake structure has become increasingly popular in such application due to its more efficient operation and more desirable performance characteristics.
Prior art and/or currently, commercially available disc brakes normally comprise a partial disc structure in which an annular brake disc is attached to a rotating wheel and is gripped by oppositely disposed arms having circular or kidney-shaped brake pads with frictional lining thereon and disposed to frictionally engage the disc located between the arms. The frictional engagement, of course, serves to retard the rotation of the wheel and cause the braking action on the vehicle. Such disc brake structures are commonly known as caliper-type brakes.
Problems resulting in the use and operation of this type of brake assembly include the inadequate dissipation of heat which is rapidly generated due to the frictional engagement between the shoe and/or lining and the disc itself. The presence of fading in a brake assembly is, of course, dangerous and various types of brake designs have been attempted in order to eliminate this problem. Another major problem recognized in the brake industry is the providing of sufficient force on the disc to provide sufficient braking action so that the brake structure can be used on heavy vehicles including airplanes, trucks, and the like. In order to accomplish sufficient force being exerted on the disc, it is academic that sufficient friction be created between the brake lining and the disc itself. In an attempt to accomplish the creation of sufficient frictional engagement, prior art devices have utilized a plurality of pistons or like structures so as to force the brake lining into engagement with the correspondingly positioned brake disc. However, problems have arisen in the design and construction of these prior art brake assemblies due to the fact that the actuating piston cannot be made sufficiently large enough to apply the proper amount of force to the brake shoes so as to provide braking action between the lining and the disc. In the above noted prior art devices it is also common to maintain the lining in a relatively fixed position relative to the rotational movement of the disc which is attached to the wheel being braked. Frictional engagement and resulting braking action occurs by linearly moving the lining into frictional engagement with the corresponding positioned surface of the disc. While such prior art brake structures are certainly operable, the amount of friction created between the lining and the disc itself is generally not sufficient for heavy duty use as set forth above over a reasonable operable life.